The present disclosure relates to devices or tools for engaging conduits or pipes. More particularly, it relates to pipe gripper tools or devices that assist workers in pulling pipes, such as when removing or pulling vertically oriented pipes.
The need to positively engage an end of a pipe arises under many circumstances. For example, installation of underground utility lines (e.g., water, sewer, gas, electrical, communications, etc.) oftentimes requires dewatering the site prior to placement of the lines. One conventional dewatering approach entails vertically inserting or boring a series of elongated plastic or metal tubes or pipes into the ground at spaced locations. The vertically oriented pipes are then fluidly connected to a larger, above ground manifold. A pump draws underground water through the pipes and manifold. Once the installation site is sufficiently dry, the pipes must be removed. Because a vast majority of the pipe length is embedded into ground, a fairly significant pulling forces is often required. Further, the pipes are relatively long (on the order of 10-30 feet in length). Large lifting construction equipment, such as a crane or boom mounted winch or backhoe, is typically employed to pull the pipes from the ground.
Conventionally, a chain is connected between the pipe and the lifting machinery (e.g., a winch hook). In particular, the chain is wrapped about the pipe's exterior at an exposed end thereof, and then mounted to the winch hook. While viable, attachment and removal of the chain relative to the pipe is time consuming, and the chain may overtly tighten against the pipe, leading to failure/breakage. Conversely, the chain may inadvertently slip off of the pipe end during the pulling process, requiring the worker to waste time re-connecting. Further, because the chain/pipe end connection point is typically high in the air following completion of the pulling efforts (e.g., 10-30 feet above ground), workers are unable to quickly disconnect the pipe from the chain. Instead, the lifting machinery must be lowered until the chain is within arm's reach. With longer pipe lengths, this is a time-consuming process, and requires a relatively large open area to complete. Perhaps more problematic, the chain may unexpectedly release from the pipe while the pipe is raised high above ground; under these circumstances, the pipe will fall to the ground, endangering any workers in the vicinity.
Though not necessarily intended for vertical pulling of dewatering pipes, efforts have been made to develop a pipe-gripping tool that engages the inner diameter or surface of a pipe for subsequent application of a pulling force. U.S. Pat. Nos. 7,232,167 and 7,396,060 are but two examples. In general terms, previous pipe-gripping tools initiate contact of tool-provided gripping surfaces with the interior surface of the pipe, with the amount of force applied to that interior surface being defined or dictated by a separate, self-contained mechanism of the tool. The gripping force is sustained by the mechanism in and of itself, and is independent of the orientation of the pipe and the separate force applying machine (i.e., the pipe and the force applicator can be vertical, horizontal, upside down, etc.), rendering user connection and subsequent release of the tool to and from the pipe's interior to be a time consuming process. The tension applied to the tool has little, if any, effect on the force on the interior surface of the pipe. While potentially viable, these prior pipe-gripping tools are not optimally configured to satisfy the constraints associated with pulling vertically-oriented pipe, or quick release of the gripping tool from the pipe when the tool/pipe connection point is located at an elevated height, such as with dewatering site pipe removal.
In light of the above, a need exists for an improved pipe gripper device for rapid engagement and disengagement of an inner surface of a pipe for use in pulling the pipe.